Pyrene and pollen observations in the pantropical genus Geophila (Rubiaceae-Psychotrieae)

Pyrene and pollen morphology of several neo- and paleotropical Geophila species is documented and discussed. Pyrenes show distinct morphological variation. They have one central or several adaxial ribs and are straight or twisted. Neotropical species only have twisted pyrenes, whereas Madagascan species have straight ones. Both pyrene types occur on the tropical African mainland and in tropical Asia. The genus is eurypalynous, including inaperturate, colpate and pantoporate pollen. The paper includes the first record of operculate pollen in the Rubiaceae, viz. in Geophila repens var. repens. Pyrenes as well as pollen morphology indicate that the varieties of the pantropical species G. repens need recognition at the specific level.